Skylight Installation Code in Georgia

Glazing Safety Requirements for Skylights

IRC Section R308.6 classifies skylights as hazardous locations for glazing. A skylight sits above occupied space. If the glass breaks, fragments fall onto the people below. This safety concern drives the glazing requirements that apply to every skylight installed on a Georgia residential roof.

Permitted Glazing Types

The code permits three glazing types for skylights:

• Tempered glass: Heat-treated to break into small, granular pieces rather than large shards. Tempered glass is 4 to 5 times stronger than annealed glass of the same thickness. It is the standard glazing for the outer pane of most residential skylights.
• Laminated glass: Two or more glass layers bonded with a plastic interlayer (PVB or SGP film). When laminated glass breaks, the interlayer holds the fragments together, preventing them from falling. Laminated glass is the standard for the inner pane of dual-pane skylights, providing the final safety barrier above occupied space.
• Wired glass: Glass embedded with a wire mesh that holds fragments together when broken. Wired glass is less common in residential skylights but meets the code requirement. It is more often used in commercial applications.

Annealed (standard float) glass is not permitted in any skylight application. Annealed glass breaks into large, jagged shards that create a serious falling hazard. A skylight installed with annealed glass violates R308.6 and will fail inspection.

Dual-Pane Configuration

Most residential skylights use insulated glass units (IGUs) with two panes. The standard configuration for Georgia installations: tempered glass on the exterior (weather side) and laminated glass on the interior (room side). This combination provides impact resistance on the outside and fragment retention on the inside. Some manufacturers offer triple-pane units with additional argon or krypton gas fills for enhanced energy performance.

The ASTM E547 standard (Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Cyclic Static Air Pressure Differential) tests the water penetration resistance of the complete skylight unit under simulated wind-driven rain conditions. Georgia code references this standard for skylight performance verification. The skylight must resist water penetration at the differential pressure specified for the building's design wind speed zone.

Glazing Type	Break Pattern	Permitted Position	Strength vs. Annealed
Tempered	Small granular fragments	Exterior pane, interior pane	4 to 5 times stronger
Laminated	Fragments held by interlayer	Interior pane (preferred), exterior	Similar strength, superior retention
Wired	Fragments held by wire mesh	Either position	Similar strength, wire retention
Annealed	Large jagged shards	NOT PERMITTED in skylights	Baseline (weakest)

Skylight Flashing Requirements

IRC R903.2 requires flashing at all roof penetrations. A skylight is a large penetration that creates a rectangular opening in the roof surface, with four edges that must be sealed against water, debris, and air infiltration. The general flashing code establishes the baseline, and skylight manufacturers provide engineered flashing systems designed for their specific units.

Manufacturer Flashing Kits

Every major skylight manufacturer (VELUX, Fakro, Sun-Tek) produces flashing kits engineered for their specific skylight models and compatible with common roof covering types. A typical asphalt shingle flashing kit includes:

• Sill flashing: A continuous piece that spans the bottom (downslope) edge of the skylight, directing water from the skylight frame onto the shingles below.
• Step flashing: Individual L-shaped pieces along both sides of the skylight, integrating with each shingle course (identical to chimney step flashing in principle).
• Head flashing: A continuous piece spanning the top (upslope) edge of the skylight, directing water flowing down the roof surface around the skylight frame.
• Corner pieces: Pre-formed corners that connect the sill, step, and head flashings at the four corners of the skylight frame.

Curb Height

The skylight curb (the raised frame that lifts the skylight above the roof surface) must extend at least 4 inches above the finished roof surface. This height prevents water pooling around the skylight base from overtopping the curb during heavy rain. On low-slope roof sections (2:12 to 4:12), higher curb heights provide additional protection against water backup. Curb-mounted skylights use a site-built or factory-built curb frame. Deck-mounted skylights integrate the curb into the skylight unit.

Ice and Water Shield

Best practice and manufacturer warranty requirements call for ice and water shield membrane (ASTM D1970) around the full perimeter of every skylight opening. The membrane extends at least 12 inches from the skylight curb in all directions, creating a waterproof collar beneath the flashing components. This secondary barrier protects against water that may migrate behind the flashing system over time.

Energy Code Requirements for Skylights in Georgia

Metro Atlanta falls in IECC Climate Zone 3, which sets specific thermal performance requirements for skylights. The Georgia State Amendments to the International Energy Conservation Code (IECC) establish maximum U-factor and Solar Heat Gain Coefficient (SHGC) values that every skylight must meet.

U-Factor: Heat Loss Performance

The U-factor measures how much heat passes through the skylight assembly. A lower U-factor means less heat transfer. For Climate Zone 3, the IECC sets a maximum U-factor of 0.55 for skylights. This means the skylight must allow no more than 0.55 BTU per hour per square foot per degree Fahrenheit of temperature difference between inside and outside.

Dual-pane skylights with low-E coatings and argon gas fill achieve U-factors between 0.35 and 0.50, meeting the Climate Zone 3 requirement. Single-pane skylights exceed the 0.55 threshold and cannot be installed in new construction or major remodeling projects that trigger energy code compliance.

SHGC: Solar Heat Gain

The Solar Heat Gain Coefficient (SHGC) measures how much solar radiation passes through the skylight as heat. A lower SHGC means less solar heat enters the building. For Climate Zone 3, the IECC sets a maximum SHGC of 0.30 for skylights. This limit controls cooling loads in Georgia's hot summers, where solar gain through a poorly rated skylight can add hundreds of dollars to annual cooling costs.

Low-E coatings on the glass surface reflect infrared radiation while transmitting visible light. A properly specified low-E skylight provides natural daylight while blocking the solar heat that drives cooling costs. Tinted glass, reflective coatings, and electrochromic (dynamic) glazing offer additional SHGC reduction for homes with high solar exposure.

Energy Performance Metric	Climate Zone 3 Maximum	ENERGY STAR Southern	Typical Dual-Pane Low-E
U-Factor	0.55	0.55	0.35 to 0.50
SHGC	0.30	0.30	0.22 to 0.30
Visible Transmittance (VT)	No code minimum	No minimum	0.30 to 0.50
Air Leakage (cfm/sq ft)	0.30 maximum	0.30 maximum	0.05 to 0.20

The NFRC (National Fenestration Rating Council) label on every rated skylight displays the U-factor, SHGC, VT, and air leakage values. Building inspectors verify these values against the Climate Zone 3 requirements during the final inspection. A skylight without an NFRC label or with values exceeding the maximums will fail the energy code portion of the inspection.

For related energy code requirements that affect the overall roof system, including insulation R-values and attic ventilation, see our insulation and energy code page.

Skylight Placement Restrictions and Best Practices

Where you place a skylight on the roof affects its water resistance, energy performance, and structural integrity. While the IRC does not specify exact placement coordinates, practical engineering constraints and manufacturer guidelines establish clear zones where skylights perform well and zones where they create problems.

Zones to Avoid

• Near the ridge (within 4 feet): Reduced deck area above the skylight limits the drainage path. Head flashing has insufficient roof surface to redirect water around the skylight. Ridge ventilation may be compromised if the skylight sits too close to the ridge vent.
• In or near valleys (within 4 feet): Valleys carry the highest water volume on the roof. Placing a skylight in a valley or immediately adjacent to one overwhelms the skylight flashing system during heavy rain. The concentrated water flow exceeds what the step flashing and head flashing can redirect.
• Near hips: Hip lines create angular geometry that complicates flashing integration. Custom flashing fabrication is required for skylights placed near hips. The cost and leak risk increase compared to mid-plane placement.
• On north-facing slopes (for solar considerations): While north-facing skylights provide the most consistent natural light with the least solar heat gain, some homeowners want south-facing skylights for passive solar heating in winter. In Georgia's Climate Zone 3, south-facing skylights require lower SHGC values to control summer cooling loads.

Optimal Placement

The best location for a skylight is centered on a clear, unobstructed roof plane, at least 4 feet from the ridge, 4 feet from any valley, and away from plumbing vents, exhaust fans, and other penetrations. This placement provides maximum drainage area above and on both sides of the skylight, simplifies flashing integration, and avoids interference with other roof components.

On homes in Buckhead, Sandy Springs, and Johns Creek with complex roof lines, finding clear roof planes for skylights requires careful planning. Your contractor must evaluate the roof geometry from both the interior (where light is needed) and the exterior (where the skylight must fit within the structural and drainage constraints) before cutting the opening.

Fall Protection and Safety During Skylight Installation

Skylight installation creates a unique safety hazard: an open hole in the roof surface. OSHA standards (29 CFR 1926.501) require fall protection at any opening in a floor, roof, or walking surface that measures 4 inches or more in any dimension. A typical residential skylight opening measures 22 x 46 inches or larger, well above this threshold.

During Installation

The period between cutting the roof opening and securing the skylight frame creates the highest fall risk. The contractor must provide one of the following protections:

• Guardrail system: A temporary guardrail around the opening that prevents workers from stepping into the hole. Practical on flat or low-slope surfaces, less practical on steep slopes.
• Personal fall arrest system: Harness, lanyard, and roof anchor that arrest a fall before the worker passes through the opening. The standard approach on steep-slope residential roofs.
• Cover: A temporary cover that supports at least twice the weight of any worker or equipment that may cross it. The cover must be secured against displacement and marked "HOLE" or "COVER."

Existing Skylights and Interior Fall Hazard

Existing skylights in attic spaces create a fall-through hazard for workers entering the attic during roof replacement, insulation, or HVAC work. The skylight well (the shaft from the ceiling to the roof surface) is an unguarded opening in the attic floor plane. OSHA requires the same fall protection measures at existing skylight wells as at new openings. Contractors who access the attic during a roofing project must identify all skylight wells and install guards or covers before beginning work.

Structural Requirements

The roof framing around a skylight opening must support the skylight load and maintain the structural integrity of the roof. The IRC requires headers at the top and bottom of the opening, spanning between the trimmed rafters or trusses. The header size depends on the opening width and the roof load. Your contractor must verify the framing before installing the skylight curb. On truss-framed roofs, cutting a truss chord to create a skylight opening requires engineered headers approved by the truss manufacturer or a structural engineer.

The bottom line: an open skylight hole in the roof is a fall hazard until the glazing unit is bolted to the curb. The contractor's safety protocol during that gap protects the crew and your home.

How 1 Source Handles Skylight Installation

When a roof replacement project includes new or replacement skylights, 1 Source Roofing manages the skylight installation as an integrated part of the roofing system, not a separate trade. This integration means the flashing system, underlayment, and shingle courses work together with the skylight as a single waterproof assembly.

Our Skylight Installation Sequence

Step 1: Before any roofing material goes down, our project manager marks the skylight location on the roof deck and verifies placement against the restrictions above. Step 2: We frame the opening with properly sized headers. Step 3: We install ice and water shield membrane around the full perimeter of the opening, extending at least 12 inches in all directions. Step 4: We set the skylight curb and secure it to the framing. Step 5: We install the manufacturer's flashing kit in sequence with the shingle courses. The sill flashing goes down with the underlayment. Step flashing integrates with each shingle course on both sides. The head flashing installs with the course above the skylight. Step 6: We install the glazing unit into the curb frame. Step 7: We verify the NFRC label values against Climate Zone 3 requirements.

Existing Skylight Replacement

When replacing an existing skylight during a roof replacement, we remove the old skylight and all existing flashing down to bare deck. We inspect the framing for moisture damage and repair as needed. We then install the new skylight using the same sequence as new construction. Reusing old flashing on a new skylight or new roof covering creates mismatched components that will leak within a few years.

For homeowners in Alpharetta, Roswell, Marietta, and other metro Atlanta communities, skylights add natural light and architectural value to your home. Proper installation to code protects that investment. A leaking skylight damages ceilings, walls, and insulation. A properly flashed and energy-code-compliant skylight performs for 20+ years without maintenance.

Related Building Code and Technical Guides

These pages cover related code requirements and technical installation standards for Georgia residential roofing:

• Georgia Residential Roofing Code Guide — Complete overview of IRC Chapter 9, permits, and inspections
• Roof Flashing Code Requirements — IRC R903.2 flashing materials, methods, and penetration details
• Chimney Flashing Code Requirements — Step flashing and counter flashing principles that apply to skylights
• Ice Barrier and Ice Dam Code — ASTM D1970 membrane specs for penetration protection
• Roof Insulation and Energy Code — Insulation requirements and energy performance standards
• Roof Underlayment Code Requirements — Underlayment standards and attachment methods
• Roof Slope Requirements — How slope affects skylight flashing performance
• Roofing Permit Requirements — Permit process for skylight installations
• Roof Flashing Installation Atlanta — Professional flashing services for metro Atlanta

Questions about skylight installation on your home? Call 1 Source Roofing at (404) 277-1377 for a free roof inspection and skylight consultation.